Big film in little pictures (4)
I believe the answer is:
epic
'big film' is the definition.
'in little pictures' is the wordplay.
'in' indicates the answer is hidden within the clue.
'EPIC' is hidden in the letters of 'little pictures'.
(Other definitions for epic that I've seen before include "Long, heroic story" , "eg The Iliad" , "Long poem etc" , "Heroic narrative verse" , "Long story telling of a hero's deeds" .)